1. Field of the Invention
The present invention relates to an optical pickup apparatus and a method of manufacturing the same. Furthermore, the present invention more particularly relates to a technique for supporting an objective lens in an optical pickup apparatus.
2. Description of Related Art
Japanese patent HEI 4-49174 describes an optical pickup apparatus that is used to reproduce or record data on an optical recording media. For example, as shown in FIGS. 1 and 2, an optical pickup apparatus typically has an objective lens 11 that is retained by a lens holder 12. A driving coil 13 for focusing operation is wound around the lens holder 12. Two pairs of driving coils for tracking operation 14 are fixedly adhered to two sides of the lens holder 12.
It is noted that the lens holder 12 is supported by a cantilever that is formed by four metal linear members 16. More particularly, the linear members 16 resiliently support the lens holder 12, and also function to supply an electric power from a fixing member 110 affixed to a base substrate to the driving coils 13 and 14 that are mounted on the lens holder 12. The linear members 16 are covered by insulation tubes such as rubber tubes 15. Base end sections 161 of the linear members 16 are affixed to the fixing member 110, and distal end sections 162 of the linear members 16 are affixed to the lens holder 12. When an electricity is supplied to the driving coils 13 and 14 through the linear members 16, a magnetic force is generated between the driving coils 13 and 14 and magnets 111. As a result, the lens holder 12 is moved by the magnetic force in a focusing direction (n a direction indicated by an arrow F) and/or a tracking direction (in a direction indicated by an arrow T) against the resilience of the linear members 16. The objective lens 11 is also moved in association with the movements of the lens holder 12 in the focusing direction and/or the tracking direction.
In the optical pickup apparatus 10 composed in the manner described above, each of the linear members 16 conventionally has a uniform cross section along the entire length thereof, as shown in FIG. 4.
However, there are problems in the conventional structure to support the lens holder 12. When the optical pickup apparatus 10 are reduced in size and thickness, the lens holder 12 becomes more difficult to properly move in the focusing direction and the tracking direction.
More particularly, when the optical pickup apparatus 10 is reduced in size and thickness, and the lens holder 12 is also reduced in size and thickness, separations between the linear members 16 in the focusing direction and the tracking direction also need to be shortened. When the separations between the linear members 16 in the focusing direction and the tracking direction are shortened, it becomes more difficult to properly control the position of the lens holder 12 when the lens holder 12 is moved in the focusing direction or the tracking direction.
For example, when the lens holder 12 is reduced in thickness, in other words, the thickness of the lens holder 12 is reduced in a direction F of FIG. 1, the distance between the linear members 16 in the focusing direction is shortened. As a result, the linear members 16 would behave move like a single linear member that supports the lens holder 12 in the focusing direction, and therefore the linear members 16 would more likely twist in the focusing direction. Accordingly, when the lens holder 12 is moved in the tracking direction, the lens holder 12 would more likely tilt.
Also, when the lens holder 12 is reduced in width, in other words, when the distance between the linear members 16 in the tracking direction is shortened, an opposite condition occurs. Namely, the linear members 16 would more likely twist in the tracking direction. Accordingly, when the lens holder 12 is moved in the focusing direction, the lens holder 12 would more likely tilt.